Prior to Jan. 1, 1994, all telecommunications switched traffic traversing through a long distance carrier network into a local exchange area was charged an “access” cost based on an equal cost-per-minute basis, with the only modification being that the so-called airline miles between the end office in the local exchange carrier network and the first switch accessed in the long distance network was taken into account. As a result, the cost that was charged to a long distance carrier was substantially independent of the actual route the traffic took through the local exchange area to the end users. Accordingly, the long distance carrier did not have to be concerned about how the calls themselves were carried by the local access providers, as long as the calls reached the end users.
All of that changed when the Federal Communications Commission (FCC) announced that after Jan. 1, 1994, the “access charges” paid by long distance carriers would more accurately reflect the true cost of access. To introduce this restructuring of the cost the FCC introduced the concept of local transport restructuring (LTR). In essence, LTR separates the switched access costs into three different components: (1) the cost charged by an access provider for a long distance carrier to use its facilities connecting a carrier's “Point-of-Presence” (POP) to a switch in the local exchange network (the “Entrance Facility charge”); (2) a fixed “per mile” cost for direct trunk lines into the local exchange area that are leased by a long distance carrier; and (3) overflow traffic volume from leased direct trunks onto the local exchange's “tandem” trunks, where this cost factor comprises both a minutes-of-use charge and a cost of the trunk groups from the tandem switch to the POP. Typically, these component costs are monthly charges, and are available to the public in published tariffs.
As of today, there is an alternative form of access network pricing, referred to as Equal Change Rule (ECR) pricing, available to the long distance carrier. Under ECR pricing, access charges are based solely on the number of minutes of use and the number of miles between a subscriber's local exchange carrier end office (EO) and the long distance carrier's POP.
In view of the changes to the cost structure, from the perspective of a long distance carrier or a wide area service provider, a cost problem has evolved that is essentially defined as a capacity problem. That is, the long distance service provider needs to determine, in advance, how many direct trunks it should lease and how much traffic should be allowed to overflow onto tandem trunks in order to achieve a specific grade of service for its subscribers, at a minimum cost. Given the fact that a long distance carrier pays out a significant portion of its revenue as “access charges”, the ability for a long distance carrier to optimize its access trunk configurations so as to minimize its access costs is of strategic importance.
Various attempts have been made to develop a rules-based approach for determining the optimal balance between direct trunks and access tandem trunks. While helpful in determining the balance for a rather “static” and predictable volume of traffic, these tools have not been able to handle the complexities associated with factors such as, for example, parallel trunk groups, multiple tandem switches for a single end office, variations in traffic peaks, day-to-day variations in traffic, or seasonal variations in traffic.
Recently, a methodology has been developed for optimizing the cost associated with access charges incurred by network service providers when leasing communications facilities from a local service provider. This methodology utilizes a pair of separate “optimization modules” that are iterated to determine the optimal arrangement on a cost basis. A first optimization module (referred to as a “sizing” module) is used to determine the optimal number of direct trunks, as well as the balance between direct trunks and access tandem trunks for each end office location. A second optimization module (referred to as a “location” module) utilizes a mixed-integer program model to determine the optimal multiplexing arrangement for a defined geographic area of the access network, such as a Local Access Transport Area (LATA). The iteration between these two modules then determines a minimum-cost switched access network arrangement between the long distance carrier and the local exchange area. The details of this approach are disclosed in U.S. Ser. No. 11/214,440 entitled “Switched-Access Network Optimization Methodology” (Florence et al.), which is assigned to the assignee of this application and incorporated herein by reference. Similar cost issues are known to arise for communication companies with respect to the leasing of “dedicated” facilities for non-switched services (such as, for example, private line service) that may carry packetized data traffic (e.g., IP, ATM, frame relay, and the like).
While the above-described Florence et al. arrangement does adjust trunk group sizes (high-usage trunk groups from EO to POP, and tandem trunk groups from tandem to POP) to reduce T1/T3 transport charges and minutes-of-use charge, it does not provide for any modifications to the actual transport network itself, where additional cost savings may be found by re-configuring the various network components.
Thus, a need remains in the art for a methodology that may be used by managers of large, complex long distance networks to optimize its use of switched and dedicated access facilities into a local exchange area, including physical changes to the network itself.